1. Field of the Invention
This invention relates to an improved on-chip detector of noise on the power supply input to the chip, and more particularly to a detector that can respond to high frequency, low magnitude noise levels and can be implemented with CMOS process technology.
2. Description of Background
An undetected noise signal introduced via the power supply to a processor, memory, or other integrated circuit, chip, can damage the chip and/or cause an error in the chip function. A typical power supply may include circuits to regulate the power supply output in order to minimize and suppress noise in the power supplied to the chip that would take the power supply voltage out of the range permitted by the chip design. Notwithstanding such power supply regulation, noise, particularly high frequency noise signals riding on the dc power supply voltage, can be coupled to the chip. As pointed out above, if undetected, such noise signals can damage the chip and/or cause an undetected error in the chip's operation. A proposal in the prior art for on-chip detection of noise signals riding on the power supply input in U.S. Pat. No. 6,605,929, employs bipolar transistors and can detect only noise signals of a large magnitude.